Birzeit University students takes cover behind the university's sign during clashes with Israeli soldiers at the Atara checkpoint close to the university as they protest against Israel's military action on the Gaza Strip, on November 19, 2012. Israeli air strikes across the Gaza Strip killed 13 people, raising the Palestinian death toll to 90 as Israel's relentless air campaign entered its sixth day. AFP PHOTO / ABBAS MOMANI (Photo credit should read ABBAS MOMANI/AFP/Getty Images)

ISRAEL/GAZA BORDER - ISRAEL - NOVEMBER 19: Israeli artillery shells attack a target in the Gaza Strip on November 19, 2012 on Israel's border with the Gaza Strip. According to reports November 19, 2012, at least 90 Palestinians have been killed and more than 700 wounded during the Israeli offensive in the Gaza Strip. (Photo by Christopher Furlong/Getty Images)

ISRAEL/GAZA BORDER - ISRAEL - NOVEMBER 19: Israeli artillery shells attack a target in the Gaza Strip on November 19, 2012 on Israel's border with the Gaza Strip. According to reports November 19, 2012, at least 90 Palestinians have been killed and more than 700 wounded during the Israeli offensive in the Gaza Strip. (Photo by Christopher Furlong/Getty Images)

Palestinians hurry away from a damaged building after an Israeli air strike in Gaza City, Sunday, Nov. 18, 2012. Israel widened the range of targets in its Gaza offensive Sunday, striking more than a dozen homes of suspected Hamas militants and two media offices, according to security officials and witnesses. The attacks also damaged adjacent houses, killing seven civilians, including five children, health officials said. (AP Photo/Adel Hana)

ISRAEL/GAZA BORDER - ISRAEL - NOVEMBER 20: (ISRAEL OUT) Israeli soldiers prepare weapons and vehicles in a deployment area as the conflict between Palestine and Gaza enters its seventh day on November 20, 2012 on Israel's border with the Gaza Strip. Hamas militants and Israel are continuing talks aimed at a ceasefire as the death toll in Gaza reaches over 100 with three Israelis also having been killed by rockets fired by Palestinian militants. (Photo by Lior Mizrahi/Getty Images)

The sun rises as an Israeli soldier washes his teeth atop a tank that he slept on, at a staging area near the Israel Gaza Strip Border, southern Israel, early Tuesday, Nov. 20, 2012. On Tuesday, grieving Gazans were burying militants and civilians killed in ongoing Israeli airstrikes, and barrages of rockets from Gaza sent terrified Israelis scurrying to take cover. Efforts to end a week-old convulsion of Israeli-Palestinian violence drew in the world's top diplomats Tuesday, with U.S. President Barack Obama dispatching his secretary of state to the region on an emergency mission and the U.N. chief appealing from Cairo for an immediate cease-fire. (AP Photo/Lefteris Pitarakis)

Palestinian firefighters try to extinguish a fire on the National Islamic Bank, destroyed overnight in an Israeli strike, in Gaza City Tuesday, Nov. 20, 2012. Early Tuesday, Israeli aircraft targeted another Hamas symbol of power, battering the headquarters of the bank senior Hamas officials set up to sidestep international sanctions on the militant group's rule. (AP Photo/Ashraf Amra)

Smoke and fire are seen from an explosion by a high rise housing media organizations in Gaza City, Monday, Nov. 19, 2012. It's the Israel's military second strike on the building in two days. The Hamas TV station, Al Aqsa, is located on the top floor. (AP Photo/Hatem Moussa)

Smoke and fire are seen from an explosion by a high rise housing media organizations in Gaza City, Monday, Nov. 19, 2012. It's the Israel's military second strike on the building in two days. The Hamas TV station, Al Aqsa, is located on the top floor. (AP Photo/Hatem Moussa)

Israeli soldiers lie on the ground as an Iron Dome missile is launched near the city of Ashdod, Israel, Monday Nov 19. 2012. Israeli aircraft struck crowded areas in the Gaza Strip and killed a senior militant with a missile strike on a media center Monday, driving up the Palestinian death toll to 96, as Israel broadened its targets in the 6-day-old offensive meant to quell Hamas rocket fire on Israel. (AP Photo/Moti Milrod) ISRAEL OUT

The dead body of a Palestinian woman from the Abdel Aal family is pulled out from the rubble after the family house collapsed during an Israeli forces strike in the Tufah neighbourhood, Gaza City, Sunday, Nov. 18, 2012. The Israeli military widened its range of targets in the Gaza Strip on Sunday to include the media operations of the Palestinian territory's Hamas rulers, sending its aircraft to attack two buildings used by both Hamas and foreign media outlets. (AP Photo/Majed Hamdan)

The dead body of a Palestinian woman from the Abdel Aal family is pulled out from the rubble after the family house collapsed during an Israeli forces strike in the Tufah neighborhood, Gaza City, Sunday, Nov. 18, 2012. The Israeli military widened its range of targets in the Gaza Strip on Sunday to include the media operations of the Palestinian territory's Hamas rulers, sending its aircraft to attack two buildings used by both Hamas and foreign media outlets. (AP Photo/Bernat Armangue)

Osama Abdel Aal is rescued after his family house collapsed during an Israeli forces strike in the Tufah neighborhood, Gaza City, Sunday, Nov. 18, 2012. The Israeli military widened its range of targets in the Gaza Strip on Sunday to include the media operations of the Palestinian territory's Hamas rulers, sending its aircraft to attack two buildings used by both Hamas and foreign media outlets. (AP Photo/Bernat Armangue)

A member of the Abdel Aal family is rescued after his family house collapsed during an Israeli forces strike in the Tufah neighborhood, Gaza City, Sunday, Nov. 18, 2012. The Israeli military widened its range of targets in the Gaza Strip on Sunday to include the media operations of the Palestinian territory's Hamas rulers, sending its aircraft to attack two buildings used by both Hamas and foreign media outlets. (AP Photo/Bernat Armangue)

A Palestinian woman walks past a building hit by an Israeli air strike in Gaza City, Sunday, Nov. 18, 2012. The Israeli military widened its range of targets in the Gaza Strip on Sunday to include the media operations of the Palestinian territory's Hamas rulers, sending its aircraft to attack two buildings used by both Hamas and foreign media outlets. (AP Photo/Adel Hana)

Explosion and smoke rise following an Israeli strike in Gaza City, Saturday, Nov. 17, 2012. Israel bombarded the Hamas-ruled Gaza Strip with more than 180 airstrikes early Saturday, the military said. The new attacks followed an unprecedented rocket strike aimed at the contested holy city of Jerusalem that raised the stakes in Israel's violent confrontation with Palestinian militants. (AP Photo/Hatem Moussa)

Smoke rises after an Israeli forces strike in Gaza City, Sunday, Nov. 18, 2012. The Israeli military widened its range of targets in the Gaza Strip on Sunday to include the media operations of the Palestinian territory's Hamas rulers, sending its aircraft to attack two buildings used by both Hamas and foreign media outlets. (AP Photo/Bernat Armangue)

Palestinian firefighters and rescue personnel work at a blast site following an Israeli air raid in Gaza City on November 17, 2012. Israeli air strikes hit the cabinet headquarters of Gaza's Hamas government, the group said early on November 17, with eyewitnesses reporting extensive damage to the building. AFP PHOTO/MARCO LONGARI (Photo credit should read MARCO LONGARI/AFP/Getty Images)

People look at a wreckage of the car in which was killed Ahmed Jabari, head of the Hamas military wing in Gaza City, Wednesday, Nov. 14, 2012. (AP Photo/Adel Hana)

People look at a wreckage of the car in which was killed Ahmed Jabari, head of the Hamas military wing in Gaza City, Wednesday, Nov. 14, 2012. (AP Photo/Adel Hana)

In this Sunday, March 11, 2012 file photo, a rocket is launched from the Israeli anti-missile system known as "Iron Dome" in order to intercept a rocket fired by Palestinian militants from the Gaza Strip in Ashdod, Israel. (AP Photo/Ariel Schalit, file)

Palestinian security forces wheel into a hospital the body of Ahmed Jabari, head of the Hamas military wing, in Gaza City, Wednesday, Nov. 14, 2012. (AP Photo/Hatem Moussa)

Palestinian security forces wheel into a hospital the body of Ahmed Jabari, head of the Hamas military wing, in Gaza City, Wednesday, Nov. 14, 2012. (AP Photo/Hatem Moussa)

Israelis soldiers run to a rocket shelter as a siren sounds signaling an attack coming from the nearby Gaza Strip in Neva settlement, near the Israel-Egypt border, Wednesday, Nov. 14, 2012. (AP Photo/Tsafrir Abayov)

Palestinian men react at hospital after the body of Ahmed Jabari, head of the Hamas military wing, was brought, in Gaza City, Wednesday, Nov. 14, 2012. (AP Photo/Hatem Moussa)

Israeli soldiers and civilians run to a rocket shelter as a siren sounds signaling an attack coming from the nearby Gaza Strip in Neva settlement, near the Israel-Egypt border, Wednesday, Nov. 14, 2012. (AP Photo/Tsafrir Abayov)

Columns of smoke rise following an Israeli air strike in Gaza City, Wednesday, Nov. 14, 2012. Palestinian witnesses say Israeli airstrikes have hit a series of targets across Gaza City, shortly after the assassination of the top Hamas commander. (AP Photo/Adel Hana)